unconfirmed_users=['alice','brian','candace']
confirmed_users=[]

while unconfirmed_users:
    current_user=unconfirmed_users.pop()
    print(f"Verifying the name of {current_user}")
    confirmed_users.append(current_user)#方法append（）后如果是列表unconfirmed——users的话，实际上是加了None，故程序无报错，但最后的输出就是连续【】

print("\nThe following users have been confirmed:")
for confirmed_user in confirmed_users:
    print(f"\t{confirmed_user}")